1. Technical Field
The present invention relates to an ink-jetting apparatus and an ink-jetting method.
2. Description of the Related Art
As a method of printing minute droplets to obtain high resolution patterns, the so-called ‘on demand’ type ink-jet printing method is currently in use. Examples of this on-demand type ink-et printing method include the piezoelectric type, thermal type and electrostatic type.
The piezoelectric type is a method of printing that provides pressure using a piezoelectric element 60 to a chamber 30 connected to a nozzle 40, and jets droplets from the nozzle 40.
The thermal type is a method for printing that heats ink and jets droplets from a nozzle by way of the pressure of a bubble generated by the heating.
For higher resolution, it is necessary to create small droplets. Thus, in the piezoelectric type or thermal type method, the diameter of the nozzle is small. However, if the diameter of the nozzle is made small, dregs may stick to the nozzle, or the nozzle may be blocked up as the ink around the nozzle dries.
Such problems may cause the direction of the jetted ink to be changed, which is directly correlated with degraded printing quality. Thus, there is a limit to realizing high resolution by decreasing the diameter of the nozzle.
The electrostatic type, on the other hand, is a printing method that generates an electrostatic force between an object and the printer head, and moves a droplet by the electrostatic force. The electrostatic type may form extremely minute droplets compared to the size of the nozzle, and there is less risk of the nozzle being blocked up.
However, when using the electrostatic type, it is hard to manufacture the apparatus because of the complexity, and there is a need for minute controlling capability. Also, there are the complications involved with manufacturing minute structures for providing a uniform amount of ink for jetting minute droplets.